Pesticide residue is often found on plants and food crops, and acceptable levels of such pesticide residue are often stipulated by regulatory bodies in many countries and in every state of the United States. Exemplary analytical methods currently used for detecting various pesticides in plant-derived samples at the regulatory limits specified by the states of Massachusetts (Mass.) and Nevada (Nev.) are illustrated in Table 1 below.
TABLE 1Exemplary Analytical Methods for Detecting PesticidesRegulatoryLimit (ppb)PesticideMANVAnalytical MethodAbamectin50LC/MS, QuechersAcequinocyl204000LC/MSBifenazate2015000LC/MS, QuechersBifenthrin2050GC-MS, LC/MS, QuechersCaptan50GC/MS, QuechersChlormequat chloride20LC/MS, MeOH/H2O/FACyfluthrin204000GC-MS, LC/MS, QuechersCypermethrin50GC-MS, LC/MS, QuechersDaminozide (Alar)20LC/MS, MeOH/H2O/FADimethomorph60000LC/MS, GC/MS, QuechersEtoxazole207000LC/MS, GC/MS, QuechersFenhexamid30000LC/MS, QuechersFenoxycarb20LC/MS, QuechersFlonicamid7000LC/MS, QuechersFludioxanil20LC/MS, QuechersImazalil20LC/MS, QuechersImidacloprid2050LC/MS, QuechersMyclobutanil209000LC/MS, QuechersPentachloronitrobenzene200GC/MS, QuechersPaclobutrazol20LC/MS, QuechersPyrethrins201000GC-MS, LC/MS, QuechersSpinetoram1700LC/MS, QuechersSpinosad201700LC/MS, QuechersSpiromesifen20LC/MS, GC/MS, QuechersSpirotetramat2010000LC/MS, QuechersThiamethoxam20LC/MS, QuechersTrifloxystrobin2011000LC/MS, GC/MS, Quechers
Quechers is an acronym that stands for Quick Easy Cheap Effective Rugged Safe and refers to a commonly used procedure for extracting analytes, e.g., pesticides, from plant-derived materials for subsequent analysis. The original Quechers method has been described in Anastassiades et al., J. AOAC Int. (2003), 86(2): 412-31, the entire contents of which are incorporated herein by reference. Quechers generally involves two steps: the first step is the production of a raw extract, while the second step is a clean-up step to remove various contaminants. The first step involves mixing with agitation a plant-derived sample with a solution comprising acetonitrile and various salts to produce the raw extract. The second step involves removing various contaminants, e.g., non-polar contaminants, from the raw extract by, e.g., solid phase extraction (SPE) to generate a solution containing the analyte of interest. The analyte of interest can then be subsequently detected and quantified by, e.g., gas chromatography and mass spectrometry (GC/MS) or liquid chromatography and mass spectrometry (LC/MS).
However, current analytical methods used for analyzing pesticide content, e.g., methods that utilize Quechers, are not suitable for detecting and analyzing certain non-polar analytes. An exemplary non-polar analyte is acequinocyl with the structure as shown below:

Acequinocyl is a pesticide found in cannabis, hops and other highly resinous dried commodities and is highly non-polar and practically insoluble in water. The clean-up step for removing non-polar contaminants used in the current analytical methods also removes non-polar analytes, such as acequinocyl, from the sample. This results in high levels of matrix interferences and leads to poor reproducibility and insufficient sensitivity of the non-polar analyte detection. Because the government-specified regulatory limits for non-polar analytes, e.g., acequinocyl present in cannabis for medicinal use, may be especially low, the current analytical methods are inadequate for ensuring that the regulatory limits are met. Furthermore, because it is difficult to achieve the required sensitivity of detection using the current analytical methods, an increased amount of sample, e.g., twice the amount, is needed for the analysis. As a result, costs for performing the analysis is overly expensive. Therefore, improved analytical methods providing both inexpensive and sensitive detection and quantification of non-polar analytes, e.g., acequinocyl, in plant-derived samples are needed.